具体可以参考https://github.com/Homebrew/homebrew/issues/21002
cd /usr/local git status git reset --hard origin/master git clean -d
homebrew update 出现Failure while executing: git pull --quiet origin refs/heads/master:refs/remotes/origin/master解决方案
原文：http://www.cnblogs.com/xiongqiangcs/p/5123035.html
